Capacitor contoller

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ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Currently we have a PFC capacitor manually controlled twice daily with a disconnect switch. 100KVAR , 200A switch, 200 amp fuses, 480V. This meets 460.8(A)(1),(2) & (3) plus the mfgs minimum.

By the looks of the knife blades I would like to put a contactor ahead of this unit. How do I size the contactor? The manufacturer recommends 169% of rated current for the disconnecting means while NEC says 135%.

A contactor is not what I would normally consider a disconnecting means but this is the closest I have found in the NEC for sizing.
 
Capacitor switching for a standard contactor is the worst thing possible.The voltage and current are phase displaced by 90 degrees and the current arc has a hard time extinguishing.This creates excessive heat and quickly corrodes the standard contact surface.Either purchase a contactor specially designed for cap switching (ie.K/M-contactor) or upgrade the standard contactor to at least 150-175%.:)
 
ptonsparky said:
Currently we have a PFC capacitor manually controlled twice daily with a disconnect switch. 100KVAR , 200A switch, 200 amp fuses, 480V. This meets 460.8(A)(1),(2) & (3) plus the mfgs minimum.

By the looks of the knife blades I would like to put a contactor ahead of this unit. How do I size the contactor? The manufacturer recommends 169% of rated current for the disconnecting means while NEC says 135%.

A contactor is not what I would normally consider a disconnecting means but this is the closest I have found in the NEC for sizing.
Click to expand...

The NEC has nothing in it about sizing contactors for controlling capacitors. It only has information on disconnect switches, fuses, and conductors.
 
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